Investigations on packet error rate of variable spreading and chip repetition factors (VSCRF)-CDMA wireless access in reverse link multi-cell environment

We apply the symbol repetition principle to the chip sequence after spreading in VSCRF-CDMA wireless access in a multi-cell environment employing one-cell frequency reuse with strong cochannel interference (CCI) from adjacent cells. More specifically, we compare three wireless access schemes: VSCRF-CDMA; DS-CDMA with adaptive transmission timing control (ATTC) achieving orthogonality among dominant paths of simultaneously accessing users; interleaved frequency division multiple access (IFDMA) only employing symbol repetition from the viewpoint of the achievable PER considering the CCI from the surrounding cells. Simulation results show that VSCRF-CDMA improves the required average received signal energy per symbol-to-interference power spectrum density ratio by approximately 1.0 and 4.0 dB compared to DS-CDMA with ATTC and IFDMA, respectively, where four simultaneously accessing users exist in the target and dominant interfering cells, respectively, in a six-path exponentially decayed Rayleigh fading channel. Consequently, VSCRF-CDMA is effective in autonomously achieving a higher link capacity in a multi-cell environment because it makes full use of the respective advantages of spreading and chip repetition.